Interactive security screening system

ABSTRACT

An interactive security screening system includes a main housing, a contact or palm pad provided on the main housing and a sample sheet positioned upon the contact pad. A sensor is operatively connected to the contact pad to measure pressure applied to the contact pad during a sample collection process. A feedback system, operatively connected to the contact pad and the sensor, provides the subject or screener with at least one of a visual signal and an audio signal to indicate whether requisite pressure was applied to the contact pad. A sample processing system analyzes the sample collection sheet through series, parallel or image processing to determine whether the trace residue sample contains a threat residue. The screening system also employs a spatial recognition system that focuses the sample processing system on particular portions of the sample collection sheet to increase overall system accuracy.

CROSS-REFERENCE TO RELATED APPLICATION

The present application represents a divisional application of U.S.patent application Ser. No. 11/525,344, filed Sep. 22, 2006 which claimsthe benefit of U.S. Provisional Patent Application Ser. No. 60/756,573filed Jan. 6, 2006 entitled “System and Method for Optimization of TraceChemical Sample Collection and Analysis in Personnel Screening andSecurity Systems.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the art of security screening systemsand, more particularly, to an interactive security screening system thatfocuses a sample processing system on particular portions of a collectedsample and employs one or more processes to screen the collected samplefor threat residue.

2. Discussion of the Prior Art

Since Sep. 11, 2001, protection against terrorist threats has become anational priority. This priority extends from the protection ofgovernment facilities inside the U.S. and abroad to the protection ofprivate businesses and venues. Various types of threats have beenpostulated, including attacks using explosive, chemical and biologicalagents, as well as nuclear and radiological (dirty) bombs. The diversityof this threat has created complex security challenges for national,state, and local governments, the transportation industry, privatebusinesses, and even individuals. Total expenditures related to HomelandSecurity topped $100B in one year and billions more have been allocatedin Federal, Supplemental Appropriations, and State/Local spending.Increasingly, U.S. businesses are devoting more revenue to securitysystems, with expenditures reaching tens of billions. Growth in thehomeland security industry is expected to be vigorous over the nextdecade. Motivated by the wide diversity of potential threats and by theinadequacy of currently available systems, government investments inresearch and development are strong.

Of the various threats postulated, explosives remain the number onechoice of terrorists. Indeed, many experts and reports have noted that,in the case of terrorist activity, the statistical evidence iscompelling, the primary threat is bombs. At present, two types ofdetection systems are in use to combat this threat, i.e., bulk detectionsystems and trace detection systems. Bulk detection systems identify thepresence of a large or threat quantity of explosives. In contrast, tracedetection systems identify the presence of residual contaminationassociated with explosives. That is, trace detection identifies whetheran object or person has come into contact with or handled explosives.

Bulk systems can cost more than $1M per portal, while trace detectionsystem generally run in the order of tens of thousands of dollars. Oftentimes, installation and annual maintenance costs will exceed theoriginal price of the system. In the case of trace explosive detection,currently deployed systems were developed primarily for the use ofanalytical chemists in laboratories and only later adapted for fielduse. Unfortunately, these systems suffer from long clearance timesfollowing a positive detection (15-30 minutes), have exceedingly highfalse alarm rates and require extensive training to ensure proper useand maintenance. Given the high price associated with the use of bulkdetection systems and their lack of suitability for many screeningtasks, such as the screening of people, trace detection systems are usedwith increased frequency and are most often selected for applicationsoutside of aviation security.

The use of trace explosive detection systems is based on widely acceptedscientific evidence indicating that handling or otherwise contactingexplosives leaves trace residue on hands, clothes, and other materialsor surfaces. The trace residue is of a high concentration and isdifficult to eradicate. The entire justification for the FederalAviation Administration's trace explosive detection program is based onthis fact. Indeed, contamination is expected to be so extensive anddifficult to eliminate that currently installed aviation trace explosivedetection systems depend on secondary contamination, i.e., contaminationtransferred from an individual's hands and clothes to their baggage.Thus, the baggage is sampled for trace explosives and subjected todetection systems for analysis. While currently deployed trace detectionsystems have high sensitivity, the systems suffer from high operationalburdens, poor sampling efficiencies, high false alarm rates and lowthroughput.

It is known that explosive contamination can vary widely over smallspatial distances. Studies have shown that trace residue levels candiffer by 10,000 fold over distances as small as a few centimeters.Unfortunately, currently available trace explosive detection systemssample only from limited spatial areas, retain no sample spatialinformation and recover samples from only a small section of the sampleacquisition surface. By sampling from only a small area, often timestrace residue is not detected even when present at detectable levelselsewhere on the sample acquisition surface. In addition, currentlyavailable sample acquisition methods are not optimized to collectparticulates in the size and size range distribution most pertinent forexplosives detection. In particular, most conventional trace detectionsystems, such as ion mobility spectrometers, require that the sampleacquisition surface be clear of substances that could interfere with themeasurement. Unfortunately, many substances that would improve theefficiency of sample recovery, such as adhesives, are not compatiblewith conventional systems and therefore cannot be utilized.

The need for a pristine sample acquisition surface or medium hasresulted in two primary sample acquisition methods employed in existingtrace detection systems such as swabbing (or swiping) an object and airjets that dislodge and test residue from an object. However, both ofthese methods are limited in sample recovery efficiency and, as statedabove, fail to retain any of the spatial information of the sample orsurface. Simple swabbing (or swiping) methods tend to leave largeparticles on the surface, typically recovering only smaller particles.Other methods, such as the above described air jet systems, often timesdislodge larger particles, but leave smaller particles on the surface.Simply put, both of these techniques fail to recover a significantfraction of the existing trace contamination.

In addition to the above described shortcomings, problems exist withsample reproducibility when using swabbing techniques. Extensiveoperator training is required to achieve even moderately reproducibleresults. The required operator training not only significantly increasesoperational costs, but the intensity of operator involvement required toobtain a good and consistent sample significantly reduces throughputrates. In any case, additional information, particularly more detailedinformation regarding a likely spatial distribution of trace samplecollection, would not only improve the probability of detection but, byeliminating areas that are not relevant and by permitting image analysisas a secondary level of processing, also improve the signal-to-noiseratio. Currently available systems do not permit such resolution.

Finally, existing systems do not to provide feedback to the operator orsubject as to the reliability of contact or the force applied duringcontact (which can impact collection efficiency) and, as such, oftenfail to achieve adequate sample recovery. In addition to preserving somespatial information about the sample, there is also a need to determinewhere, on the sampling surface, the trace contamination is most likelyto be present. In conventional swabbing systems and in novel systemsthat enable wider area analysis, such information would improve thesignal-to-noise ratio of the analysis by focusing the detection andanalysis on the area with the highest likelihood of contamination and byeliminating background signals that can cause unnecessary false alarms.

Therefore, despite the existence in the art of security screeningsystems, there still exists a need for an improved security screeningsystem. More specifically, there exists a need for an interactivesecurity screening system that provides feedback to test subjects andfocuses detection on portions of a sample that are most likely tocontain trace or threat residue.

SUMMARY OF THE INVENTION

The present invention is directed to a interactive security screeningsystem including a main housing, a contact pad provided in the mainhousing and a sample collection sheet positioned upon the contact pad.To initiate a screening process, a subject is asked to contact thesample collection sheet which then collects and retains a trace residuesample for analysis. A sensor is operatively connected to the contactpad and configured to measure a pressure applied to the contact padduring a sample collection process. In accordance with the invention,the screening system includes a feedback system operatively connected tothe contact pad and the sensor. The feedback system provides the subjector screener with at least one of a visual signal and an audio signalindicating whether a proper sample has been collected.

Once a proper sample is collected, the sample is passed to a sampleprocessing system which scans and analyzes the sample collection sheetto determine whether the trace residue sample contains a threat residue.The sample processing system includes an analyzing portion that employsseries processing when maximum scanning accuracy is desired, parallelprocessing when maximum throughput is necessary or image processing whenit is particularly advantageous to remove areas which are not ofinterest from the sample prior to screening or evaluation. Regardless,the screening system employs a spatial recognition system that focusesthe analyzing portion on particular sections of the sample. In thismanner, the overall accuracy of the screening system is increased,thereby resulting in fewer false positive results which tend to slow thescanning process, inconvenience individuals and place an unnecessaryburden on security personnel.

Additional objects, features and advantages of the present inventionwill become more readily apparent from the following detaileddescription of preferred embodiments when taken in conjunction with thedrawings wherein like reference numerals refer to corresponding parts inthe several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an upper left perspective view of a screening center includinga dynamic user feedback and processing system constructed in accordancewith the present invention;

FIG. 2 is a cross-sectional side view of the screening center of FIG. 1;

FIG. 3 is a detailed view of a palm sensor portion of the screeningcenter;

FIG. 4 is a representative view of a sample obtained during a screeningprocess employing the screening center of FIG. 1;

FIG. 5 is a block diagram outlining a screening process in accordancewith one aspect of the present invention;

FIG. 6 is a block diagram outlining a screening process in accordancewith another aspect of the present invention; and

FIG. 7 is a block diagram outlining a screening process in accordancewith yet another aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As will become more fully evident below, the present invention can takevarious forms in connection with scanning for various potential threats.However, initial reference is made to FIGS. 1 and 2 in describing asecurity screening center or kiosk 2 constructed in accordance with apreferred embodiment of the present invention. Screening center 2includes a main housing 4 provided with a front wall 6, a rear wall 7, atop wall 8, a bottom wall or base 9 and opposing side walls 10 and 11.In addition, screening center 2 is provided with various accessories toenhance an overall aesthetic appearance of main housing 4 and helpscreening center 2 blend in or match a particular venue or location. Forexample, in the embodiment shown, screening center 2 is shown with apair of columns 17 and 18, that, in connection with various coloredplaques or murals (not shown) attached to either rear wall 7 or sidewalls 10 and 11, provide a readily adaptable enhanced aestheticappearance to screening center 2 that matches or blends with theparticular venue at which screening center 2 is deployed.

Screening center 2 includes a sample collecting portion 34 arrangedwithin a housing 37 that retrieves trace residue samples and, in certaininstances, demographic samples from a subject. As such, collectingportion 34 includes a residue sample collector 38, a demographic samplecollector (not shown) and an output portion 45 which, as will bedescribed more fully below, outputs or issues an article to the subjectupon completion of a screening process.

In accordance with the invention, residue sample collector 38 includes asample collecting sheet 55 positioned upon a palm pad 56. A pressure orpad sensor 57 is arranged below palm pad 56 and, as will be detailedmore fully below, functions to provide feedback to the subject during asample collection process. In order to protect sample collecting sheet55 from various environmental factors, palm pad 56 is positioned below acowl 58. To ensure proper sample screening, fresh sampling media isprovided for each screening process. Towards that end, sample collectingsheet 55 is provided on a continuous roll 59 including a first spool ornew media portion 61 and a second spool or used media portion 62 whichare separated by a shield 65 and a seal 67. Tension is applied tocollection sheet 55 by a pair of tensioning rollers 70 and 71, whileguide rollers (not separately labeled) are provided to ensure properpositioning upon palm pad 56. Application details of the overallstructure operation and application for security center 2 can be foundin commonly assigned U.S. patent application Ser. No. 11/418,193 filedon May 5, 2006, now U.S. Pat. No. 7,545,280, incorporated herein byreference.

In a manner that will be discussed more fully below, after obtaining asample, sample collecting sheet 55 is moved to a sample processingsystem 75 including an analyzer portion 78. As shown, analyzer portion78 includes a housing or light proof chamber 82 within which ispositioned an applicator 87 and an image capturing unit or scanner 89.Arranged below image scanner 89 is a clear shield 92. Another shield 95separates applicator 87 from image scanner 89. A heater 100 is mountedto an underside of clear shield 92. Heater 100 is activated whennecessary to warm agents applied by applicator 87 or to warm the samplesheet to facilitate the screening process. In a manner that will bedescribed more fully, below, during the screening process, analyzerportion 78 performs one of several pre-programmed scanning processes onthe sample. The particular process employed depends upon variouscircumstances, such as desired accuracy, throughput or the presence ofcontaminants. In any case, following analysis of the sample, acontroller portion 101 determines whether the sample contains a threatresidue.

In order to ensure the collection of a proper sample, palm pad 56includes pad sensor 57 having a pixel array 110 operatively coupled tocontroller 101. More specifically, upon approaching screening center 2,a test subject places his or her hand upon palm pad 56 and appliespressure to sample collection sheet 55. Preferably, sample collectionsheet 55 is provided with an adhesive coating selected for moderatetackiness and skin contact compatibility and in order to minimizebackground fluorescence or luminescence. In addition, sample collectionsheet 55 may have embedded therein various catalysts or precursors tosupport subsequent analysis or processing steps. For instance, zincparticulates or powder can be employed.

To ensure that sufficient pressure has been applied over a wide enougharea for efficient sample recovery and to improve reproducibility ofsample acquisition, screening center 2 includes a dynamic feedbacksystem 112. If necessary, feedback system 112 provides visual and/oraudible queues to the subject when additional pressure should be appliedto palm pad 56. That is, the pressure applied to palm pad 56 must be ofa sufficient force so as to obtain a suitable sample. Visual cues can beprovided on a screen portion 113′ provided in housing 4 or, as statedabove, audible cues, such as “apply more pressure,” can be signaled fromscreening center 2. In any event, once the subject has appliedsufficient pressure, a proper sample 114 is obtained.

In order to maximize sample analysis, screening center 2 also includes aspatial recognition system 115 (see FIG. 3) that performs a spatialanalysis on sample 114. Spatial recognition system 115 utilizes pixelarray 110 on pad sensor 57 to designate particular areas of interest onsample 114, such as A1-A8 (see FIG. 4). More specifically, studies haveshown that particular portions of a hand are more likely to includetrace residue than others. Thus, spatial recognition system 115 enablesanalyzer portion 78 to focus on particular points of interest A1-A8 ofthe obtained sample 114 in order to increase the reliability of thescreening process. Once spatial analysis is complete, sample collectionsheet 55 is shifted into analyzer portion 78 and the screening processcontinues.

In accordance with the invention, analyzer portion 78 employs one ormore processes when screening sample 114. The particular processemployed depends upon a desired depth of analysis, a required level ofthroughput or other security demands. More specifically, if there is aneed to maximize a probability detection, series processing, such asillustrated in FIG. 5, is preferably employed by analyzer portion 78.Alternatively, analyzer portion 78 can also be programmed to performparallel processing (FIG. 6) when high throughput is desired. Finally,image processing, illustrated in FIG. 7, which digitally removespotentially interfering substances (or areas unlikely to contain thedesired sample) from the detection process to compensate for processinconsistencies or background imperfections, can be employed, eitheralone or in combination with another analysis process. In general, imageprocessing both increases detection accuracy and reduces false alarmrates.

As best shown in FIG. 5, serial processing involves sequentially passingsample 114 through a chemical application and illumination process. Thatis, after designating areas of interest A1-A8, sample collection sheet55 is moved into analyzer portion 78 where a first chemical applicationprocess 140 is initiated. Following application of one or more chemicalagents, sample collection sheet 55 is illuminated in step 143. Otherprocessing steps, particularly the activation of heater 100 to activatea particular applied chemical agent or otherwise aid in analysis, areperformed in step 146. After processing step 146 is complete, an imageis acquired by image scanner 89 and analyzed for threat residue in step149. This overall process can be repeated one or more times withdifferent chemical applications, depending upon a desired level ofaccuracy and the particular trace residue of interest. Upon completionof series processing, analyzer portion 78 outputs a result 157 tocontroller 101. Result 157 can be presented to the test subject on akeepsake (not shown) that is issued through output portion 45 or,alternatively, passed to a central security station (not shown) forreview and further analysis.

As stated above, if higher throughput is required, for example in orderto expeditiously accommodate larger crowds, analyzer portion 78 can beprogrammed to perform parallel processing on sample 114. As best shownin FIG. 6, after designating areas of interest A1-A8, sample collectionsheet 55 is passed to analyzer portion 78 for an initial chemicalapplication process step 163. During chemical application process step163, multiple chemical agents 165-167 are substantially simultaneouslyapplied to sample collection sheet 55, even as it passes. Followingchemical application process step 163, sample collection sheet 55 isilluminated in step 175 and subjected to various additional processingsteps at 180, such as the activation of heater 100 to activate thechemical agents. Illumination step 175 and processing steps 180 can berepeated one or more times depending upon the chemicals employed anddesired level of accuracy. After illumination and processing steps 175and 180 are complete, an image is acquired during an image acquisitionstep 184. Once the image is obtained, analyzer portion 78 determineswhether sample 114 contains a threat residue in step 188. The result ispassed to controller 101 and, in a manner similar to that describedabove, either imprinted upon a keepsake which is issued to the testedsubject or passed to a central control center.

Reference will now be made to FIG. 7 in describing an image processingdetection method employed by analyzer portion 78. In a manner similar tothat described above, after designating areas of interest A1-A8, samplecollection sheet 55 is passed to analyzer portion 78. At this point, afirst image capture of sample 114 is performed in step 198. First imagecapture 198 is conducted employing white light. Preferably, imagescanner 89 is configured to utilize a visible wavelength. The imageobtained in step 198 is used to identify any physical contaminants thatmay be present on sample sheet 55 which might result in false alarms inthe final result. Sample collection sheet 55 is then exposed toultraviolet (UV) light in light proof chamber 82 in step 202. At thispoint, it should be noted that all image capture steps could beperformed in light proof chamber 82, with only the particular type ofillumination, i.e., white light, UV light, changing as necessary. In anycase, while sample collection sheet is exposed to UV light, a secondimage is captured in step 205. Preferably, image scanner 89 is sensitivein a wavelength range that is specific for potential interference, suchas white light contaminants that may fluoresce when subjected to UVlight and contaminates that may absorb UV light. These potentialinterferences are image captured prior to step 209.

In step 209, a detection image is captured under the UV light usingimage scanner 89 which is preferably set to the same wavelength employedwhen capturing image 205. However, various other wavelengths can bechosen in order to optimize detecting optical changes consistent withtrace explosive residues. In any event, once obtained, the three imagesare digitally analyzed in digital processing portion 212 for evidence oftrace explosives. The images are correlated using one or more commonreference points on all images. Preferably, the common reference pointsare registered in a calibration portion of internal hardware andsoftware, but may also be registered using one or more of designatedareas A1-A8 or pre-made marks on sample collection sheet 55.

The first images obtained in steps 198 and 205 are used to identify andremove any visible contaminants from the final image obtained in step209. More specifically, the image obtained in step 209 is used toidentify and remove any fluorescent and/or UV absorbing contaminantsfrom the final image such that the known and identified contaminants aredigitally removed from the detection image. The resulting image is thenanalyzed for evidence of trace explosive content. Once complete, theresult is passed to controller 101 and, in a manner similar to thatdescribed above, either signified on a keepsake or passed to a centralprocessing portion.

It should be recognized that the security screening center constructedin accordance with the present invention is readily adaptable to variousvenues and/or security levels employing one or more processing steps inorder to ensure a high level of reliability while, simultaneously,increasing throughput through screening center 2. In addition, byproviding feedback to test subjects to ensure proper sample recovery andemploying a system that focuses on particular areas of a sample that aremost likely to contain threat residue, the security system increases thelikelihood of identifying potential threats. Furthermore, it should berealized that sample processing in accordance with the invention can bedone on individual samples, such as with the various process stepsdescribed above being performed on a moving sample or in sample batcheswith multiple samples being concurrently processed.

Although described with reference to preferred embodiments of theinvention, it should be readily understood that various changes and/ormodifications can be made to the invention without departing from thespirit thereof. In general, the invention is only intended to be limitedby the scope of the following claims.

1. A method of obtaining and analyzing a sample from a subject throughinteraction with an interactive security screening system comprising:pressing an object associated with the subject upon a sample collectionsheet positioned over a contact pad, said object exerting an amount ofpressure upon the contact pad; sensing the amount of pressure applied tothe contact pad through portions of the sample collection sheet;analyzing whether the amount of pressure sensed is sufficient toindicate that a proper sample has been obtained on the portions of thesample collection sheet; and analyzing the portions of the samplecollection sheet with a sample processing system that scans the propersample for threat residue.
 2. The method of claim 1, further comprising:performing at least two cycles of chemical application followed byillumination in determining whether the sample collection sheet includesa threat residue.
 3. The method of claim 1, further comprising:substantially simultaneously applying multiple chemical agents to thesample collections sheet; illuminating the sample collection sheet; andacquiring an image in determine whether the sample collection sheetincludes a threat residue.
 4. The method of claim 1, further comprising:capturing at least two images of the sample collection sheet.
 5. Themethod of claim 4, further comprising: capturing each of the at leasttwo images employing different wavelengths of light.
 6. The method ofclaim 1, further comprising: selectively configuring the sampleprocessing system to employ one of series processing, parallelprocessing and image processing.
 7. The method of claim 1, furthercomprising: selectively re-configuring the sample processing system fromemploying one of series processing, parallel processing and imageprocessing to another of series processing, parallel processing andimage processing.
 8. The method of claim 1, further comprising:providing a signal to the subject if a requisite amount of pressure isnot applied to the sample collection sheet.
 9. The method of claim 8,further comprising: providing one of an audio signal and a visual signalwhen the subject does not apply the requisite amount of pressure to thesample collection sheet.
 10. The method of claim 1, wherein the samplecollection sheet is taken from a roll of disposable sample collectionsheets.
 11. A method of obtaining and analyzing a sample from a subjectthrough interaction with an interactive security screening systemincluding a main housing, a contact pad provided on the main housing, asample collection sheet positioned upon the contact pad, a pressuresensor operatively linked to the contact pad, a sample processing systemand a spatial recognition system operatively connected to the sampleprocessing system, said method comprising: receiving a trace residuesample upon contact of the sample collection sheet with a subject;utilizing the pressure sensor to determine a pressure applied to thecontact pad by the subject during a sample collection process; utilizingthe spatial recognition system to focus the sample processing system onparticular portions of the sample collection sheet including the traceresidue sample; and analyzing only the particular portions of the samplecollection sheet with the sample processing system to determine whetherthe trace residue sample contains a threat residue.
 12. The method ofclaim 11, further comprising: providing at least one of a visual signaland an audio signal concerning a proper sample collection through afeedback system operatively connected to the sensor.
 13. The method ofclaim 11, further comprising: serially processing the sample through atleast two cycles of chemical application and illumination.
 14. Themethod of claim 11, further comprising: parallel processing the samplethrough at least one step wherein multiple chemical agents aresubstantially simultaneously applied to the sample collection sheet. 15.The method of claim 11, further comprising: image processing the samplethrough at least two image capture steps.
 16. The method of claim 15,further comprising: employing illumination at two separate wavelengthsin the at least two image capture steps respectively.
 17. The method ofclaim 11, further comprising: employing one of series processing,parallel processing and image processing with the sample processingsystem.
 18. The method of claim 11, further comprising: selectivelyactivating a heater of the sample processing system to facilitate threatresidue detection.
 19. The method of claim 11, wherein the samplecollection sheet is taken from a roll of disposable sample collectionsheets.
 20. A method of obtaining and analyzing a sample from a subjectthrough interaction with an interactive security screening systemcomprising: pressing an object associated with the subject upon a samplecollection sheet positioned over a contact pad, said object exerting anamount of pressure upon the contact pad; sensing the amount of pressureapplied to the contact pad to assure that a proper sample has beenobtained; analyzing the sample collection sheet with a sample processingsystem that scans the proper sample for threat residue, wherein thesample processing system is only directed to particular portions of thesample sheet for scanning; and performing at least two cycles ofchemical application followed by illumination in determining whether thesample collection sheet includes a threat residue.